Question

solve the following equation if theta lies between 19 and 540 degree cos 2theta -sin2 theta=cos theta-sin theta-1.
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Answer 1

${\red {AHOY}}$ ✌️

${\huge {\mathfrak {Answer :-}}}$

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Suppose, thita = A.

➡️ cos 2A - sin 2 A = cos A - sin A - 1

➡️ cos^2 A - sin^2 A - 2 sin A cos A = cos A - sin A - sin^2 A - cos^2 A

➡️ 2 cos^A - 2 sin A cos A = cos A - sin A

➡️ 2 cos A ( cos A - sin A) = (cos A - sin A)

➡️ 2 cos A = 1

➡️ cos A = 1/2 = cos 60°

➡️ A = 60°

.°. Thita = 60°

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Thanks..